Diseases caused by the Leishmania-Trypanosoma complex are of major importance in the Wester Hemisphere. The diseases exhibit marked variation in clinical manifestations yet, taxonomically, biochemically and immunologically, they maintain many similarities which may provide clues to pathogenesis. Control of these diseases will result from careful evaluation of pathogenic mechanisms, antimicrobial therapy, disease patterns, and methods of accurate diagnosis. This program project brings together basic science and clinical investigators from Cornell University Medical College and The Rockefeller University and respected Brazilian investigators from the University of Bahia and the University of Brasilia. The central focus of this collaborative effort is the integration of basic and applied clinical research. The major research areas include: 1) basic parasitology, immunobiology and pharmacology of Chagas' disease and leishmaniasis; 2) clinical disease patterns, epidemiology and genetics these disease; and 3) application of immunologic techniques for understanding pathogenesis and for reliable diagnosis. Central to this grant is the attempt to coordinate the activities of investigators from different disciplines to allow exchange of limited resources, to bring these investigators in contact with young researchers abroad, and to advance our understanding of important human diseases.